Philip osoae jenkins



. (No Model.)

P. 0. JENKINS.

INGANDESGENT ELECTRIC LAMP. l

y Patented June 28, 1887.

lill/lll lllllllllll/ UNITED STATI-:s

PATENT OFFICE.

PHILIP OSCAR JENKINS, OP WASHINGTON, DISTRICT on COLUMBIA.

lNCANDESCENT ELECTRIC LAMP.

SPECIFICATION forming part of Letters 4Patent No. 365,384, dated June28, 1.887.

A Application tiled July 23, 1886. Serial No. 208,833. (No model.)

provements in Incandescent Electric Lamps;

and I do hereby declare that the following is a full, clear, and exactdescription of the invention, which will enable others skilled in'theart to which it appertains to make and use the. same, reference beinghad tothe accompanying drawings, and to the letters of reference markedthereon,which form part of this speciiication.

lVIy invention relates to incandescent lamps, and has for its object tofurnish a lamp of this class which will give forth a larger volume oflight than heretofore, and which will be convenient and practical inuse.

It consists incertain details of construction, arrangement, andcombinations of parts and application of new materials, which I shallnow proceed to fully describe, and the specific points of noveltyinwhich willv be particularly designated in the claims.

Referring to the accompanying drawings, Figure 1 is a perspective viewof my invention complete. Fig. 2 is an enlarged sectional view of thesame with the rubber tubing detached. Fig. 3 is a detail perspective ofthe inside plate,having the end of the soapstone cylinder insertedtherein. Fig. 4 is a detail view of the soapstone cylinder. f Fig. 5 isa detail View of one of the metallic tubes for conducting the gases intothe'rubber tubes. Figs. 6

and'7 are detail views of different forms of my` carbon electrodes. Fig.8 is a view in perspective of the manner of forming my mica casing. Fig.9'is -an end view of same, showing the projecting or overlapping ends ofmica before it is secured down.

Likeletters of reference mark the same parts in all the figures of thedrawings.

Referringto the drawings by letter, A is the shell orv casing of mica.

b b are the metallic caps,` the average thickness of which is shown insection in Fig. 2.

' C C are the electrode-wires piercing the ends of cap b b, and d d isthe carbon electrode interposed between the wiresC C, protectedby anexternal insulated graphite shell, and having each end in contact withthe wire electrodes, said ends of electrode d each projecting through acentral perforation in each of the two disks e', made of insulatingsubstance interposed between the graphite and soapstone casings.

eis the casing, of graphiteor other suitable substance, inclosing thecarbon-insulated pencil d.

ff are the soapstone cylinders, having one of theirends respectivelypiercing the metallic plates g g, which serve t'o keep the plaster orother plastic material from rising up in themica tube, and to press thematerial iirml y against the inside of the rim and bottom of themetallic caps b b.

h h are the rubber tubes which receive and hold excess of carbon oxideor the gases conducted by the metallic tubes 'i fi from within the micacasing. These tubes M have one end, i', larger than'the other, t, theobject of which is to form a support for the ends ofthe rubber tubes.This rubber tube, the ob ]ect of which has been partly explained, is ofa Avery elastic nature, being capable of great -distention, andconsequently of an Increase of capacity; and it may be attached to thelamp, as shown, or may be secured` only at one end, .having the otherfree and plugged up to prevent the ingress of air, thereby freeing thelamp from all danger of bursting by the expansion of heat. y

D are modified forms of my carbon pencils, the advantages and uses ofwhich will be hereinafter fully explained.

It is well known to those skilled in the art to which this inventionappertains that the required resistance in an electrode for producingintensity of light cannot be obtained eX- ceptin a small electrode orits equivalent in character or capacity, and that the maintenance ofthelight cannot be had unless in a vacuum or its equivalent; and,furthermore,

it is known that this equivalent has not hitherto been discovered andutilized; and it will be obvious that a device that will accomplish thisresult is of great advantage and importance in incandescentlighting, andthis is the IOO ing of a cleavable nature, I carefully separate itslaminte into very thin pieces, thereby obtaining the requiredelasticity, which enables me to properly roll it into form withoutbreaking orinjuringit. As shown in Figs. S and 9, it is formed byrolling tightly around a smooth unyielding cylinder of the size requiredwith reference to the intended size of the lamps, then rolling it uponitself several times in a convoluted state. Rubber bands are thenapplied, or some suitable material is passed around its ends to sustainthe eylind rical forms alreadygained. The unyieldingcylinder upon whichthe mica has been wrapped is then withdrawn, leaving a hollow cylinderof mica of great firmness, one end of which is inserted into a metalliccup filled with some suitable plastic material. The electrode is thenintroduced and put into electrical contact with this cup by firmlytouching its central surface or piercing it, as preferred, and theopposite end thereof is similarly treated.

Having proceeded thus far (premising that I have introduced a smallhollow tube in one or both ends, which communicates with the spaceinside) I fasten a thin rubber tube, first pressing out the air thereinand hcrmetically sealing it, its office being semi-vicarious, ashereinafter explained. The free edge of the mica left by wrapping isglued down upon the other layers of same, so that there may be nopossible ingress of air.

The increase ofthe volume of light and the maintenance of thesainc for acorrespondingly greater length of time is obtained by the einployment ofcarbon pencils of from one-eighth to one-sixteenth of au inch indiameter, surrounded by a shell of the same or similarsubstance,(graphite beingpreferred, )which isprovided with an aperture of somewhatgreater diameter than the electrode inserted therein. Then this shell(when not of the refractory non-eondncting oxides) is insulated both atits ends and upon its inside cylindrical surface. The former is done byintcrposing a solid substance of insulation similarly perforated, sothat the small electrode within the shell may pass through it to thewires or poles, and the latter, by coating the small inclosedresisting-conductor with a coating or paste of the oxideofzirconiuin,aluminum, or any other insulating refractory substancesuitable therefor. This arrangement prevents a loss of rcsistance in theinclosed pencil-conductor, al lowing it its full power of conducting theheat generated by the electrical current at once to the shell, whichshell becomes incandescent and gives forth from its larger surface amuch greater volume of light than can be economically gained by theordinary methods on a small electrode alone. sVhen it is desired toincrease the resistance on an electrode quite large, and at the sametime to maintain its size, the diameter is reduced, as will be seen bythe accompanying drawings.

The lamps are preferably made three and one-half inches in length, themica being better adapted for this size than glass, and 1n dition, itmay be said that a small lamp 1s more unyielding to pressure thanalargerone.

To avoid the combustion of the electrode and the shell, Ido not producea vacuum by exhausting the air, but obtain an equivalent by reducing orconverting the oxygenhwhich supports combustion, into carbonic oxide, 1nwhich form it is a nonsupporter of combustion, and, together with thenitrogen present, has its only obstacle or disadvantage 1n the expansiveproperty awakened by the heat within. This disadvantage is entirelyovercome, as before explained.

To effect the equivalent of a vacuuni 1n a lamp whose small amount ofair is inadequate to more than supply a start toward theeombustioncarbons within, it is only necessary to subject myconstruction of carbon electrode and shell to the action of theelectrical cur rent for a few moments, which will produce all combustionthat can take place, and there remain only two gases-wiz,carbonic-oxideand nitrogen, neither of which will produce or support combustion. Thisresult 1s comparativel y easy to obtain where the size of the carbonswithin the lamp is too large for thc quantity of air; and thisnon-combustiblecondition will remain indefinitely, so long as there canbe no ingress of air inthe lamp,whieh contingency is carefully guardedagainst 1n the construction.

Having thus fully described my invention, what I claim as new, anddesire to secure by Letters Patent of the United States, is-

1. The method, substantially as described, of forming the cylindricalexternal mica casing, which consists in first separating the lam1- me ofthe mica into thin elastic sheets or layers, which are then rolled orfolded around an unyielding eyli nder of suitable size and shape, thensecuring the said folds or layers together by gluing or otherwise,whereby 'a hollow transparent elastic mica cylinder or casing otsuitable diameter and shape is formed for incandescent electric lamps,as set forth.

2. The combi nation, with suitable electrodes, of a carbon bodyprojecting at each end through a central perforation in a disk, asshown, surrounding the easing of said electrodes, as set forth.

3. The combination, with suitable electrodes and an insulated body ofcarbon interposed between said electrodes, of an insulated. graphitecasing surrounding the said insulated carbon body, as set forth.

4. The combination,with suitable electrodes, of a carbon body projectingat cach end through a central perforation in a disk surrounding thecasing of the said electrodes, having its diameter centrallyreduccd,with the insulated graphite or other carbon casing, as setforth.

5. The combination of suitable electrodes, an insulated body of carboninterposed between said electrodes, having its diameter reduced betweenits extremities and insulated casing surrounding said body, and'suitablesoapstone or other cylinders surrounding the electrodes and supported atone end in the- 'between said electrodes, a casing for saidbodyinsulating material at each end of the carbon body, and a suitablecylinder for incasing the electrodes, as described.

8. The combination of an incandescent lamp having transparent micainclosing shell, suitable electrodes, an interposed carbon body betweensaid'electrodes enveloped with a graphite casing, andenvelopingcylinders for said electrodes, with a glass reservoir consisting ofrubber tubing impervious to air and communicating with the chamber ofsaid lamp, as set forth.

`9. The combination ofthe gas-reservoir consisting of rubber or othertubing impervious to air and communicating with the chamber of thelamps, with an incandescent lamp, as described.

In testimony that I claim the foregoing as my oWn I affix my signaturein presence of two witnesses.

PHILIP OSCAR JENKINS.

/Vitnesses:

0. E. DUFFY, MJ.` CALLAN.

